1. Two solutions: a) Leave the CZ, run 500 metres away and call an Apex taxi. b)blow yourself up (lower shields, drop a grenade or stand next to a red barrel and shoot it). You will respawn in the Frontline dropship and there will be an option to withdraw from combat zone.
2. Not as far as I know - long-standing glitch. Better to leave, come back and start again.
Good luck o7